# A018528 (b-file synthesized from sequence entry) 1 1 2 2 3 3 4 4 5 6 6 8 7 9 8 12 9 16 10 18 11 24 12 32 13 36 14 48 15 64 16 72 17 96 18 144 19 192 20 288 21 576